Ion Exchange Resins for Advanced Removal of Nanoparticles from UPW? – A Novel Imaging Approach

Nanoparticles represent one of the most critical contaminations in ultrapure supplies for semiconductor fabrication addressing ultrapure water (UPW), gasses and chemicals as well as materials of construction decreasing yield on the wafer. Along the UPW generation process, there are sources (e.g. materials) and sinks (e.g. filter) for nanoparticles. As final barrier for nanoparticles in the polishing step, ultrafilters are commonly used on UPW plants. However, the performance of the ultrafilters in the field in terms of removal performance for particles need to be investigated to come up with pro-active approaches for particle removal. Especially for UPW, there is a lack of online particle metrologies down to particle size of sub 50 nm. This study aims to give an overview on different particle metrologies to better understand the particle removal performance by ultrafilters on the market.

Critical feature sizes of modern semiconductor devices have surpassed the capabilities of traditional optical-based methods to measure particle concentrations in process chemicals and on wafers. Without adequate metrology for quantifying particle and particle precursor concentration in process chemicals, device makers face challenges correlating component failures and fabrication steps. This is especially true for organic material released by Final Polish Ion Exchange resin during a rinse cycle, which is not detected efficiently using optical methods. In this work, we describe two state-of-the-art measurement methods that can detect organic particles and particle precursors to 3 nm using Aerosolization and Threshold Particle Counting (TPC) and defects from UPW deposited on a wafer surface down to 8 nm using Surfaced Enhanced Particle Sizing (SEPS)

UF even withstands episodic increase of particle numbers in the feed (e.g., caused by conditioning of ion-exchange resins) without negative effects for water quality and service lifetime. Such a particle challenge typically involves high concentrations of ~10-nanometer (nm) particles. On the other hand, current on-line particle counters approach their lower detection limit at about 10nm. Large numbers of particles nearby and below this limit remain undetected. Hence, the integrity of a UF membrane is essential to keep these small particles under control; it can hardly be evaluated by comparing particle counts upstream and downstream. Therefore, better test methods are needed to identify membrane damages, and to decide on service life and replacement of UF membranes.

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the ultrapure water strand.

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the airborne molecular contamination (AMC) and high purity gases control strand.

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the ultrapure water strand.

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the ultrapure water strand.

This presentation was given as part of the Ultrapure Micro 2021 annual conference. It was given as part of the ultrapure water strand.

Ultrapure water (UPW) is one of the main materials for electronics fabrication and therefore, it needs to be monitored for critical parameters such as nanoparticles (NP). The state-of-the-art online measurement techniques are challenged by particles at the killer particle sizes smaller than 10 nm. Due to the uncertainties in NP detection, the identification of NP sources and sinks in UPW system is limited nowadays. This review article aims to give an overview on the current developments and perspectives in metrologies for detection and control. The following topics will be discussed: transferability of general definition of NP to UPW, state-of-the-art particle analytics, sources and sinks of NP in UPW systems as well as dominant particle interactions responsible for NP contamination. This article was originally published in the Ultrapure Micro Journal in November 2017.

This article provides an overview of the biggest challenge of UPW technology – particle control. The latest semiconductor technologies require near particle-free water, where the “killer” particle size is far below the size that UPW metrology can effectively detect. Also, current advanced treatment methods cannot guarantee reliable removal of killer-sized particles. The quality of the high-purity materials used downstream of the final filters has not typically been tested for shedding of the “killer” particles. Consequently, the semiconductor industry requires a comprehensive approach for the particle control. A new approach should include mitigating particle occurrence and continuously improving the technologies used in UPW polish and distribution systems. Such an approach should also include extensive use of SEMI standards to improve the quality of the materials used; a new way to engineer solutions related to system-configuration and system design; improved process control; and a careful review of critical operational decisions. Collaboration throughout the industry via IRDS and SEMI Standards is key to enabling such systematic improvement, and overcoming the metrology and other constraints. This article was originally published in the Ultrapure Micro Journal in November 2017.